Method for assembling miniature tubing



Oct. 1, 1968 F. WIELAND ET AL 3,404,055

METHOD FOR ASSEMBLING MINIATURE TUBING Filed Aug. 17, 1967 2Sheets-Sheet 1 m k5 R g 5? M INVENTORS FRANZ WIELAND JOSEPH J. CIOLJACOB W. ZANSITIS ATTORNEYS 0a. 1,1968 F. WlELAND ETAL 3,404,055

METHOD FOR ASSEMBLING MINIATURE TUBING Filed Aug. 17, 1967 2Sheets-Sheet]? Q5 w N L. N R

' INVENTORS FRANZ WIELAND OSEPH J. CIOL OB W. ZANSITIS ATTORNEY$ UnitedStates Patent 01 ice 3,404,055 Patented Oct. 1, 1968 METHOD FORASSEMBLIN G MINIATURE TUBING Franz Wieland, Bethlehem, Pa., Joseph J.Ciol, Parlen,

N.J., and Jacob W. Zansitis, Easton, Pa., assignors to Rapidograph,Inc., Bloomsbury, N.J., a corporation of New Jersey Filed Aug. 17, 1967,Ser. No. 661,372 9 Claims. (Cl. 156-294) ABSTRACT OF THE DISCLOSUREMethod of assembling miniature tubing in co-axial alignment,particularly assembling of jewel points in stainless steel holders asused in stylographic writing instruments, the outside diameters of saidjewel points being in the range 0.0080.052 of an inch.

Background of the invention (1) Field of the inventin.This inventionrelates to the fitting of relatively brittle jewel-type points instylographic writing instruments, particularly the secure fitting ofjewel points having an outside diameter of 0.008 of an inch or lesswithout crimping of metal fasteners about the brittle jewel pointenabling drawing of a consistently fine line over contemporary draftingmedia.

The present invention is the result of a demand for increasingly finerlines in technical drawing. Contemporary drafting media include a coatedMylar plastic film which rapidly abrades conventional stainless steeltips. Jewel points have been used before, but manufacturing difficultieshave been encountered with jewel points having an outside diameter ofless than 0.010 of an inch. According to the present invention, jeweltips having an outside diameter in the range 0.008-0.0520 of an inch aresecurely fitted in stainless steel holders, enabling the writing oflines of uniform width for distances up to one mile over Mylar draftingfilm, including the fine line drawn by jewel points 0.008 of an inch indiameter.

(2) Description of the prior art.-Paul, 2,600,426: Directed to thefitting of jewel points in stainless steel holders wherein a conicaljewel is secured to a metallic capillary tube by means of flaring areduced neck of the capillary tube outwardly at its end so as to overliea portion of the rounded end of the jewel. According to thisarrangement, the metallic capillary tube extends throughout the entirejewel and overlaps the jewel in its core area. A basic shortcoming ofthis arrangement is that as the jewel wears and the neck of thecapillary tube wears, the flared out end is worn off, resulting in aloose fitting or the falling off of the jewel. Also, the tapered surfaceof the jewel precludes its Writing a line of consistent width as itbecomes worn. The insertion of the metallic capillary tube through thejewel requires an increase in the diameter of the jewel and precludesits adaptability for small diameter writing points.

Young, 3,292,595: Concerns the insertion of metallic carbide tips instainless steel holders and specific-ally describes the difliculty offorming jewel points with a relatively thin wall in the order of say.004 of an inch required to form a thin line of approximately .008 of aninch. According to Young because of extreme tolerances and extreme care,as well as the impossibility of swedging the jewel into its fitting incommercial production, the jewel tip is unsatisfactory for many draftingrequirements. It is pointed out that the swedging of the jewel in ametallic fitting would cause destruction of the jewel, especially as thediameter of the jewel is reduced to those diameters, e.g., .008 of aninch attainable in tungsten carbide and like metallic fittings.

Great Britain, 1,045: Concerns the fitting of a drilled jewel, forexample, metal, vulcanite wood or ivory in a setting formed of gold. InGreat Britain 1,045 the jewel is tapered, precluding the writing of aconsistently thin line, also the crimping or fitting of the gold aboutthe face can result in a fracture of the jewel and, of course, the goldfitting could not be sufficiently hard to enable use of the resultinginstrument in automated drafting machines.

Summary of the invention According to the present invention, a housingis formed from a larger sized diameter tube such as a stainless steeltube by counterboring its core at one end to an inner diameterapproximating the outer diameter of the jewel tube to be fitted. Thejewel may be a smaller size diameter tube, having its wall as thin as0.002 of an inch, an inner diameter or core of 0.004 of an inch and atotal outer diameter of 0.008 of an inch. The housing is locked againstmovement, then the jewel is threaded on an elongated wire mandrelextending through the core of the jewel and coaxially towards the lockedhousing. Epoxy resin glue is placed on the exterior or periphery of thejewel tube, care being taken to avoid placing of glue on the ends of thetube. The jewel is then advanced with the mandrel into the housing. Themandrel is then removed and the housing is set in a vertical position.The glue is then cured and, finally, the jewel tip is radiused bybrushing with diamond paste.

Extremely close tolerances, in the range of 0.0002- 0.0005 of an inchare required to be maintained in order to achieve the necessary closefitting of jewel and holder components.

Brief description of the drawings FIG. 1 is an enlarged perspective viewof the jewel fitting, showing the writing instrument casing in phantom;

FIG. 2 is a longitudinal cross-section, showing one type of jewelassembly seated within its stainless steel housing;

FIG. 3 is a longitudinal section of another type of jewel fitting in astainless steel housing; and

FIG. 4 is a longitudinal section of yet another form of fitting,according to the present invention.

Description of the preferred embodiments Jewel housing 10 may bemachined from stainless steel or other metal to include interior core 12and elongated neck extension 14 defining Ia counter-bored jewel housing16 with a radially outwardly extending shoulder 19, intermediate thecore 12 and housing 16. Jewel housing 10 may be tapered inwardly as at22 so as to provide a beveled edge encircling the cylindrical jewel 25which includes wall 24, core 26 of equivalent diameter to core 12 andwriting end 28 having a radially inwardly extending radius 30.

Housing 16 is machined so as to provide a flat bottom shoulder 19essential for complementary engagement with the corresponding bottom 32of jewel 25. Jewel 25 may be machined as a true cylinder withoutanterior radiused tip or writing edge, jewel cylinder 25 having a wallthickness as thin as 0.002 of an inch and an interior diameter or coreof 0.004 of an inch, making an overall outer diameter of 0.008 of aninch.

Prior to fitting, jewel 25 is cleaned by boiling in nitric acid forapproximately 10 minutes, then rinsed clean under water and finallycleansed with a cleaner such as Du Pont cleaner trademarked Vyathene.Jewel 25 is then threaded onto an elongated wire mandrel, illustrated inphantom in FIGS. 2-4, and with the mandrel protruding in front of thejewel approximately 0.100 of an inch towards the core of housing 16which is then fixed against movement. With jewel 25 on the wire mandrel,both wire mandrel and jewel are pushed towards the jewel housing. Athermosetting epoxy resin is then applied on the outer periphery ofjewel 25 at three spaced points. lPlacing of the epoxy on either end 32or 28 of the jewel tube is studiously avoided. After gluing, jewel 25and the wire mandrel are inserted into housing 16. The extrusion of themandrel beyond jewel end 32 and into core 12 of the holder 10, alignsjewel 25 coaxially with holder 10, as well as its housing 16. Jewel 25is then pressed into housing 16 so that jewel end 32 abuts and fitsfirmly against inner shoulder 19 within the housing. Excess epoxy, ifany, is urged radially inwardly onto chamfer 18 and, thus, does notsubsequently interfere with the fiow of ink through coaxially alignedcore 12 and core 26. The mandrel is removed and excess epoxy formingaround the juncture between the leading edge or shoulder 22 of thehousing and jewel 25 periphery is removed.

Housing and jewel are then supported with the jewel 25 extendingvertically upwardly so as to permit the epoxy to gravitate downwardlytoward shoulder 19. Then, the epoxy may be heat set or cured bysuspending the entire assembly within a heating furnace, for example, ata temperature of 250 F. for two hours. Thereafter, shoulders on thejewel are radiused smooth by means of diamond paste and brushing. Afterradiusing, jewel 25 and housing 10 are cleaned again with Vyathene orsimilar cleaner and inspected by shadowgraph. To insure that the bore isclear, the wire mandrel is inserted through the jewel tube core 26 andinto core 12 so as to remove any diamond paste particles that may nothave been removed by cleaning.

As an illustration of the dimensions achievable and the tolerancesrequired, jewel 25 in FIG. 2 can have an outer diameter of 0.0100 of aninch with a tolerance of plus or minus 0.0001 of an inch. Radius 30 isin the area of 0.0015 of an inch with a tolerance of 0.0002 of an inch.Tube core 26 inner diameter is 0.0060 of an inch plus or minus 0.0002 ofan inch. The outer diameter to the inner diameter is within 0.0005 TIR(total indicator reading). Jewel assembly 24 is 0.021 of an inch inlength plus or minus 0.001 of an inch.

Housing 16 has a depth of 0.0135 of an inch plus or minus 0.001 of aninch. The entire housing 10 is 0.246 of an inchthe outer diameter of thehousing base portion 11 is 0.0216 of an inch, plus or minus 0.0005 of aninch and the outer diameter of neck portion 14 being 0.0170 of an inchplus or minus 0.0005 of an inch. The inner diameter of core 12 is 0.0060of an inch plus or minus 0.0005 of an inch. The inner diameter ofhousing 16 is 0.0109 of an inch, plus or minus 0.0001 of an inch(housing 16 inner diameter and jewel 25 outer diameter being within0.0002 TIR), thus assuring a sliding fit of jewel 25 within housing 16.

It is obvious that other methods of assembly can be employed to obtainthe same results as those disclosed. For instance, instead of firstthreading the jewel tip on the mandrel and having the mandrel protrudeapproximately 0.100 of an inch from the jewel tip :and pushing themandrel and jewel toward the housing, the mandrel could be inserted intothe core of the housing and then the jewel tip could be threaded on thefree end of the mandrel, glue applied to the jewel tip and then thejewel tip could be pushed into the housing.

In addition, the radiusing of the jewel tip, the proportions of thehousing and jewel fitting may be varied without departing from thespirit and scope of invention, as defined in the sub-joined claims.

We claim:

1. Method for assembling miniature tubing of varying diameters incoaxial alignment, comprising:

(a) forming a housing from a larger diameter tube by counterboring itscore to an inner diameter 4 approximating the outer diameter of asmaller diameter tube; (b) locking said larger diameter tube againstmovement;

(0) threading the smaller diameter tube on an elongated mandrelextending through the core of said smaller diameter tube;

(d) applying glue to exterior side portions of said smaller tube;

(e) advancing said mandrel and said smaller diameter tube coaxiallytowards said larger diameter tube;

(f) urging said smaller diameter tube coated with glue into thecounterbored core of said larger diameter tube so that a portion of saidsmaller diameter tube extends outwardly of said larger diameter tube;and

(g) removing said mandrel from both said tubes.

2. Method for assembly miniature tubing as in claim 1, includinglongitudinally extending said mandrel towards said larger diameter tubeand beyond the end of said smaller sized diameter tubing approximately0.100 of an inch.

3. Method for assembling miniature tubing of varying diameters as inclaim 1, including forming a radially extending shoulder within saidlarge size diameter tube intermediate its core and an inner end of saidhousing.

4. Method for assembling tubing as in claim 3, including radiusing aleading edge of said portion of said smaller diameter tube extendingoutwardly of said larger diameter tube.

5. Method for assembling tubing as in claim 4, wherein said radiusing isaccomplished by brushing within the range .0015 to .008 of an inch.

6. Method for assembling miniature jewel tubular points in tubularholders comprising:

(a) forming a housing in a large diameter tubular holder bycounterboring its core to an inner diameter approximating the outerdiameter of a smaller jewel tubular point;

(b) locking said larger diameter tubular holder against movement;

(c) threading the smaller diameter jewel tubular point on an elongatedmandrel extending through the core of said smaller diameter jewel tube;

(d) applying glue to exterior peripheral portions of said smallerdiameter jewel;

(e) advancing said mandrel and said jewel coaxially towards said largerdiameter tube;

(f) urging said jewel coated with glue into the counterbored core ofsaid larger diameter tube so that a portion of said smaller diameterjewel extends outwardly of said tubular holder;

(g) removing said mandrel from both said jewel and said tubular holder;

(h) curing said glue; and

(i) radiusing by brushing the leading edge of that portion of said jewelextending outwardly of said tubular holder.

7. Method for assembling jewel tubular points in tubular holders as inclaim 6, including vertically suspending said tubular holders with saidjewel point uppermost after gluing, so as to enable gravity flow of saidglue about said jewel within said housing.

8. Method for assembling jewel tubular points in tubular holders as inclaim 7, including final cleaning of jewel tubular point and tubularholder core by inserting said mandrel axially therethrough.

9. Method for assembling miniature tubing of varying diameters incoaxial alignment, comprising:

(a) forming a housing from a larger diameter tube by counterboring itscore to an inner diameter approximating the outer diameter of a smallerdiameter tube;

(b) locking said larger diameter tube against movement;

(c) inserting an elongated mandrel into core of said larger diametertube;

(d) threading the smaller diameter tube over the free end of saidmandrel;

(e) applying glue to exterior side portions of said smaller tube;

(f) urging said smaller diameter tube coated with glue into thecounterbored core of said larger diameter tube so that a portion of saidsmaller diameter tube extends outwardly of said larger diameter tube;and

(g) removing said mandrel from both said tubes.

References Cited UNITED STATES PATENTS Andrews et al. 401-265 X Kaufman156-294 X Higgins 156-294 X Kovacs 401-265 Paulsen 401-265 X Roller401-265 Delaruelle et al. 156-294 X HARQLD ANSHER, Primary Examiner.

